Posted by: Sophie Khatib21 OCT 2012
Wow. I’m amazed. A tv programme that gives a visual representation of what goes on inside a cell – personally it brings information together from multiple modules...everything is clicking into place!
It’s fascinating looking ‘inside a cell’ and comparing the size differences of various structures. Looking at the inhalation of an adenovirus. Recognising the different cells of the immune system and the different roles they play. Security proteins on the surface of a cell membrane. Seeing the evolution of viruses in order to cross the cell membrane. I find it absolutely amazing that every cell in our body carries out such tasks without us being aware of a single thing!
It really brings home how finely tuned and important each and every cell in our body really is and how much of a purpose they have. They seem to behave like a city: processing information, reducing intruders, setting on specialised roles within the cell as a whole, back up and checking proteins and keeping the most important information hidden away.
The adenovirus, while being so common, is amazingly specialised and clever in its desire to hijack the replication machinery in the host cell. It seems to take advantage of the defence mechanisms in the host cell and use these to its advantage. For example, using the acid released from the endosomes of a cell to allow disintegration of the virus and release of proteins used to damage the walls of the endosome. This allows free entry into the cell and thus bypasses this important step in the cells defence.
I was completely unaware of the internal immune system of a cell. It appears that a specific protein, p21, can search for anything expressing antibodies or other such structures and signal to proteosomes to break down the foreign molecule. The proteosome will then degrade the virus in a few hours and recycle any components that are of use to the cell. Despite this internal immune system, it only takes one cell with no antibody expression to bypass this system and reach the cell nucleus in order to exert its effect over the body.
Since the viral DNA is so similar to host DNA, the cell cannot distinguish between the two and the viral DNA codes for destruction of the host cell. Once the ribosomes work from the viral genetic information, functional proteins are accurately made and folded. The virus has now made the toolbag for its attack on the body. The virus can actually halt any processes inside the nucleus that it does not need – normal processes that the cell would be undergoing in normal circumstances. The cell membrane then becomes the site for signalling to the world outside the cell that it has undergone invasion by a virus or bacteria.
Since the normal processes are being halted by the viral genetic information, the cell begins to die and so this signalling shows the other cells what is going on inside and alerts the body as to what is going on – a final attempt to save the body from this viral invasion!
I don’t think it would be humanly possible to ever invent anything this complex with as many “just in case” processes as a backup. The more I learn about things like this, the more fascinated I am!